Medical research on the subject of nourishment during prolonged exercise has shown that hydration with a carbohydrate-rich hypotonic fluid—i.e., a “sports drink”—is the most effective technique for preventing dehydration and minimizing fatigue. Dehydration may be of three types: hypotonic, which is characterized by a loss of electrolytes, sodium in particular; hypertonic, which is characterized primarily by a loss of water; and isotonic, which is characterized by an equal loss of water and electrolytes. Hypotonic dehydration may be prevented by proper consumption of hypotonic fluids. Hypotonic fluids contain electrolytes, which allow cells to generate energy and electricity. Consuming hypotonic fluids causes muscles to contract, circulates water and fluids throughout the body, and provides numerous other benefits that help athletes maximize endurance. Carbohydrates may also help prevent hypotonic dehydration. Carbohydrates are the fuel for human metabolism and the primary source of energy for the human body. Among the most common carbohydrates is glucose, a simple sugar (monosaccharide).
As sports have grown in popularity, increased attention has been focused on developing hypotonic fluids rich with carbohydrates. Sports drink manufacturers generally attempt to develop products that include optimal amounts of electrolytes and carbohydrates. However, many sports drinks are high in calories, and consuming them in excess poses risks and drawbacks for athletes. To overcome this challenge, athletes may carry both water and a sports drink when engaging in prolonged exercise.
One technique for carrying and dispensing these fluids that has gained popularity over the last twenty years is the use of a hydration pack. See, for example, U.S. Pat. No. 5,085,349 A issued Feb. 4, 1992, by Fawcett entitled “Resilient Valve and Dispensing System for Bicyclists;” U.S. Pat. No. 8,267,283 B2 issued Sep. 18, 2012, by Staton, entitled “Personal Hydration System;” U.S. Pat. No. 7,631,672 B2 issued Dec. 15, 2009, by Spencer, entitled “Portable Hydration System with Resupply System;” D,547,606 S issued Jul. 31, 2007, by Forsman entitled “Bite Actuated Mouthpiece;” U.S. Pat. No. 6,364,168 B1 issued Apr. 2, 2002, by Gardner et al., entitled “Personal Hydration System with an Improved Mouthpiece;” U.S. Pat. No. 6,874,760 B2 issued Apr. 5, 2005, by Steckel, for “Angled-Slit Bite-Valve;” and U.S. Pat. Nos. 7,533,786 B2 and 7,658,303 B2 issued May 19, 2009, and Feb. 9, 2010, respectively, by Woolfson, et al., entitled “Personal Water and Additive Apparatus.”
A hydration pack generally includes a fluid reservoir in the form of a bag and a hose attached at or near the bottom. The hose is typically designed to be long enough to reach the user's mouth. Fluid is dispensed to the user through a valve connected to the end of the hose. The valve is usually made from an easily deformable material such that when it is compressed by the users' mouth or teeth, the fluid can be drawn from the reservoir at will.
The reservoir may contain all types of drinkable fluids. However, fluids containing any form of carbohydrate (e.g., sugar in common sports drinks) often leave behind a sticky residue that may be difficult or impossible to remove from the reservoir. The residue may affect the flavor and composition of any liquid subsequently kept in the reservoir. If left uncleaned, the residue may cause bacteria to grow within the reservoir and contaminate its contents. Consequently, many users of personal hydration systems only fill the reservoir with water and carry a supplemental supply of electrolytes and carbohydrates in a separate container. This approach limits the utility of the hydration pack, since the user must carry two separate items.